2...d5 or 2...Nf6 is probably just a matter of taste. See the thread "1.d4 f5 2.Nc3 can black spice this up?" below for the discussion.

Just curious. What is best for a Leningrad player after 1.d4 f5 2.Nc3 Nf6 3.Bf4 (instead of the standard 3.Bg5)? Probably 3...g6 or 3...d6. Of course, an early g6 often invites a quick h4 (does not look that dangerous here), while after 3...d6 White could try 4.f3!? preparing e4. Anyone have anything on this?

I agree with Björn completely. Later you can play Ne7-Nc8-Nd6, which is a good square for the knight.

This weekend I faced an interesting move order in the 2.Nc3 Dutch. After 1.d4 f5 2.Nc3 Nf6 3.Bg5 d5 4.Bxf6 exf6 5.e3 Be6 6.Qf3 Nc6 my opponent played 7.Nge2. In the game 7...Qd7 8.Nf4 0-0-0 9.Nxe6?! Qxe6 10.0-0-0!? followed after which black has no problems.
However I believe that white could have played much better by heading for the game Malaniuk-Jakubiec 1999 with 9.Bb5, white keeps black from moving the knight and prepares to castle kinside (no hurry though). Black will usually regret to have castled queenside so early.

So, if it's not such a good idea to castle as early as I did (which I believe is indeed the case), then what else can one do?
8...Ne7 9.h4! looks horrible for black, he can't block the h4-h5 advance with h7-h5 as he usually would in the Nc3-Dutch, the same goes for 8...Rd8. In both cases 9.g5 would presumably be too risky (while after 8...0-0-0 9.h4 it should have been fine).
Maybe one could try 8...Bb4, or does 9.h4 work after that too?

Or should black perhaps vary earlier (e.g. 6...Qd7 instead of 6...Nc6 or something else instead of 7...Qd7)?

7.Nge2 looks quite interesting, 7.Bb5 and 7.Bd3 seem to give black more options.